The present invention relates to optical scanners and more specifically to a dual aperture optical scanner.
Optical scanners are well known for their usefulness in retail checkout and inventory control. Optical scanners generally employ a laser diode, the light from which is focused and collimated to produce a scanning beam. An optical transceiver directs the beam against a mirrored polygon or spinner and then against a plurality of stationary mirrors, and collects the beam after it is reflected by a bar code label. A motor rotates the mirrored polygon, and a detector receives the returning beam. The pattern produced by such a scanner is characterized by lines oriented at various angles to one another.
Typically, optical scanners emit light through one aperture, either horizontal or vertical, but not both. In high performance scanners, light is emitted from several directions through this aperture. In the case of horizontal apertures, a pattern of light is projected onto the front and bottom surfaces of a labelled item. In the case of vertical apertures, a pattern of light is projected onto the front and side surfaces of a labelled item. In low performance scanners, light illuminates only the surface which is facing the aperture.
Unfortunately, scanners having one aperture require item orientation to ensure that the bar code label is properly aligned in relation to the aperture. Orientation time slows item throughput and therefore customer throughput. Item orientation may also cause repetitive strain injury.
Therefore, it would be desirable to produce a high performance optical scanner having two scanning windows which illuminate the bottom and sides of a labeled item, thereby minimizing item orientation and increasing throughput.